The Role of Probiotics in Parkinson's Disease: A Review Study

An upward trend in the incidence of Parkinson’s disease (PD), known as one of the most prominent neurodegenerative maladies, has evoked great concerns among medical community over the past decades. Recently, studies have suggested the initiation of PD in the gastrointestinal tract decades before the advent of manifestations. Accumulating evidence suggests that intracellular deposition of α-synuclein (α-syn) in patients with PD is associated with systemic inflammation leading to the neuroinflammation and neuropsychiatric disorders. The α-syn protein accumulation can be initiated from GI cells and distribute into CNS cells through trans-synaptic cell to cell transmission. Without doubt, gut microbiota affects the enteric nervous system (ENS) known as the “second brain”. Patients with PD have a different balance of bacteria in their intestines, as compared to healthy population. Metabolites from gut microbiota affect the enteric wall such as neurodegeneration. Probiotics have a substantial role in the neutralization or inhibition of reactive oxygen species (ROS) and free radicals and thus improve the PD symptoms. The anti-inflammatory role of probiotics also inhibits the neurodegeneration and PD development. Hence, probiotics contribute to the improvement of PD through several mechanisms which need more in-depth verification.